Posts have been used, of course, with signs for many years. The idea of extending a lateral cross arm from the top of a post and hanging a sign from the cross arm was probably conceived more recently. However, sign posts which hold signs from a lateral cross arm have been known in the prior art.
In the field of real estate, sign posts with lateral cross arms for holding signs became common in the 1970's. One such sign post used 4".times.4" redwood lumber for both the vertical member and the horizontal cross member. A notch the width of the lumber was milled half-way into each piece so that when bolted together the two pieces were in the same plane. The two pieces were transported as a single assembly in an automobile. At the installation site, the vertical member was placed in a pre-drilled over-sized hole with loose dirt tamped around it. A real estate "For Sale" sign was then hung from screw eyes screwed into the laterally extending cross member.
The problem with the redwood sign post is that it was heavy and difficult to implant in the ground. Often, there were difficulties in drilling the installation hole, especially in winter. Not only was this a difficult chore, but removal of the sign post was also difficult when the ground was frozen. Furthermore, in wet weather, the sign post was top-heavy and tended to tip over as a result of the loosely tamped soil around the base of the vertical member.